Threatening the opposition's signal-caller is the goal of every defensive lineman on every play, causing disruption, havoc and confusion in the offense. Over the last 17 years, Purdue has fielded several outstanding defensive ends, creating a tradition unlike any other in college football.

The Boilermakers' Den of Defensive Ends has become a talent-rich, nationally feared group of Purdue standouts, including Rosevelt Colvin and Chike Okeafor in the late-1990s and continuing to unanimous All-American and 2011 NFL first-round draft pick Ryan Kerrigan.

Colvin and Okeafor started the tradition in 1999, heading into the NFL after outstanding collegiate careers. Okeafor was a second-team All-Big Ten pick in 1996, while Colvin owns the season sacks record with 15 in 1998, as well as the career mark with 35 from 1995 to 1998. Colvin is forever enshrined in Purdue football history for his part in the miraculous 22-21 come-from-behind victory over Michigan State in 1997, scooping up a blocked field goal and taking it 62 yards to paydirt.

Both were selected in the 1999 draft, with Okeafor going in the third round to the San Francisco 49ers, and Colvin following in the fourth round to the Chicago Bears. Okeafor spent 11 years in the league, starting 111 of 150 career games for the 49ers, Seattle Seahawks and Arizona Cardinals. He racked up 53 sacks in his career, posting a top mark of 8.5 sacks twice, first with Seattle in 2004 and again with Arizona in 2006. Colvin spent 10 years in the NFL, playing four seasons with the Chicago Bears and another six with the New England Patriots. He had back-to-back huge seasons in Chicago in 2001 and 2002, becoming the first Bear to have double-digit sacks in consecutive years since Richard Dent in 1990 and 1991, and went on to become a member of the Bears' All-Decade Defensive Team. Colvin won a pair of Super Bowl rings with the Patriots and is one of just 20 Boilermakers in school history to play for a World Championship squad.

The tradition followed in 2002 and 2004 as Akin Ayodele and Shaun Phillips were selected in the third and fourth rounds of the NFL draft, while Ray Edwards and Rob Ninkovich went in the fourth and fifth rounds in 2006. The four have accounted for more than 100 combined sacks, including Phillips's 56.5 while playing for the San Diego Chargers. Phillips was named to the 2011 Pro Bowl after recording 55 tackles and 11 sacks.

The next three members named to the esteemed club were 2007 first-round draft pick Anthony Spencer, 2008 third-round selection Cliff Avril and Kerrigan. Spencer was the first Boilermaker grabbed in the opening round of the NFL Draft since Rod Woodson in 1987, being taken 26th overall by the Dallas Cowboys. In his first six seasons in the league, he has become a fixture of the Cowboy defense, starting 67 games, including 61 of his last 62 over the last four years. Avril followed his den-mates into the pros in 2008, being selected by the Detroit Lions, where he earned a starting spot on one of the most improved defensive fronts in the league before recently signing with the Seattle Seahawks.

Kerrigan had a monster career in Old Gold and Black, matching the NCAA career record with 14 forced fumbles, including a NCAA-best seven in 2009, in addition to 57 career tackles for loss and 33.5 career sacks. His resume was good enough to make him the No. 16 pick in the 2011 NFL Draft and he's gone on to thrive for the Washington Redskins, earning a spot in the Pro Bowl earlier this year.

But the legacy of great defensive ends at Purdue goes back much further than the mid-1990s, so this year, a group of Purdue football historians selected three more players to add to the mix, representing the earlier eras for Boilermaker football. Leo Sugar (1949-51), Lamar Lundy (1954-56) and Keena Turner (1976-79) were All-Big Ten defensive ends who went on to play collectively for 30 years in the NFL. All three have been inducted into the Purdue Intercollegiate Athletics Hall of Fame.

Sugar was an 11th-round draft choice of the NFL Chicago Cardinals and went on to play eight years with the Cardinals, Philadelphia Eagles and Detroit Lions (1954-62). Lundy, who was Purdue's Most Valuable Player of 1956 and is now deceased, was drafted in the fourth round by the Los Angeles Rams and starred for 12 years as a member of the "Fearsome Foursome" (1957-69). Turner, the Boilermakers' MVP of 1978, was a second-round pick of the San Francisco 49ers and played for 10 years (1980-90) with the same team, winning four Super Bowl championship rings.

All 12 of members of the Den of Defensive Ends have gone on to outstanding NFL careers, and have made Purdue a hot spot for professional talent at the position.

Over the coming months, Purdue intends to invite all living members of "The Den" back to campus to be recognized for this distinction and for their role in Boilermaker football lore. In conjunction with that, a calendar, T-shirts and other apparel and merchandise will be produced to commemorate this tradition with proceeds going toward the 12th Boiler Fund in the John Purdue Club to help endow a football scholarship.